To develop an in vitro assay of lymphocyte stimulation and inhibition by immune stimulators and repressors. To determine the mechanism of action of the immune stimulators and repressors. To test new drugs for in vitro immune stimulatory and repressive activity. To apply the knowledge obtained about the mechanism of action to develop new drugs that would be more active in the treatment of cancer. To isolate and purify a factor from tumor cells that inhibits the multiplication of normal lymphocytes. To determine if immune stimulators can hasten the return of immune competence. To determine if levamisole works through a Beta adrenergic receptor.